I've been researching squatter's rights, or "adverse possession", for the past while. Seems like under current Canadian law, every province has it's own rules, but generally it takes about 10+ years. And yeah, BC is impossible to get squatter's rights in.
I think most people have been using adverse possession laws for fences and other miscellany. Actually squatting on someone's land for 20 years would be a third of your life, anyway, and probably the commune wouldn't last that long.
Crown Land, or public land in Canada, is a different mountain of red tape. Seems like most provinces have similar-ish rules for "applying" for Crown Land, but most Canadians seem very cynical about the prospects of doing it. Seems like, sure, you can apply -- but you need to get a whole bunch of ecological / environmental surveys done. Seems a bit expensive.
Salamat has an interesting idea about just buying a cheap mineral claim. I don't know how that works, exactly, but I'm going to do more research on it (I see many adds on Kijiji for this -- still seems like a scam, though).
I also found a few stories of guys who just went out and built a cabin somewhere. One guy, in Ontario, was spotted in the MIDDLE OF NOWHERE up past Timmins near a lake and, of course, in good "safe" Canadian fashion, the person reported him. He got fined.
Another was a Norwegian guy who flew into the most desolate lake he could find in NWT, and built his own cabin and lived there for 6 months.
Yet another guy built a treehouse on the side of a hill near Squamish, BC, and apparently was living off-grid up there. Nice little hide-away.
Overall, I think you can get away with it, usually, but if you're caught they'll kick you out, fine you, and probably burn the place down (that's what all the old timers in Ontario say, anyway.....)
My current plan is to use one of the concepts in applying for Crown Land, that being "for tourism and recreational purposes", and make a wilderness hostel. Then, you can have a group of rad people, and more rad people from across the world. Go canoeing and have bonfires and dance around like mad people.
If the Crown land idea doesn't pan out, I've got 50k saved so far, but fuck, it's not our parents' or grandparents' age: land is fucking EXPENSIVE pretty much everywhere -- especially in BC (where I'd like to live, i.e. warmer winters). Most land I see on REALTOR.ca or ZILLOW.com, for even about 5-10 acres, seems to be about 50-100k, and waterfront (which is essential for me) doubles that, at least. Even more upsetting than the price tag is that all this private land is usually small, awkwardly cut-off from other bigger chunks of land, or part of planned new cottage country / subdivision developments (long fingers of land).
But, I guess if this quest was easy everyone would do it.
Hope you haven't given up on that dream!